The present invention relates to a portable terminal apparatus of battery-powered type.
In conventional portable terminal apparatuses of this type, power is supplied for a CPU constantly from a battery while a power supply is turned on thereby to drive an oscillation circuit normally. The oscillation circuit, therefore, consumes electric power all the time regardless of the operation of the CPU.
In order to meet the present-day demand for smaller and lighter industrial equipment, however, portable terminal apparatuses are required to be reduced in power consumption.
The portable terminal apparatuses now in use comprises a C-MOS device and consumes electric power increasing in proportion to the operating frequency. Although a lower frequency is a measure for reducing the power consumption, the processing speed of the CPU would be decreased. The disadvantage of the conventional portable terminal apparatuses, therefore, cannot be obviated simply by reducing the power consumption.